Abrasive article of manufacture



fl- 1950 r G. J. GOEPFERT ETAL 2,520 ,763

ABRASIVE ARTICLE OF MANUFACTURE Filed' May 19, 1948 INVENTORS 650265 J. GOEPF'ERT y Laws L. Cor/m Patented Au. ,,29, 1950 Falls,

.N. Y., assignors to The Carborundum.

'companyrNiagai-a Falls, N. Y., a corporation of Delaware Application May 19, 1948, Serial No. 21,907

" 11 Claims. (c1. sis- 9s This invention relates to abrasive discs comprising an annular abrasivelvelement adhesivelysecured ,to a backingwhich isrelativelyrthin and lightweight incharacterhand comprises several .5 a thin metallic platebuilt into the'central part of the discto constitute apart of the .backing.

laminations of fibrous material. The backing is not. of sufiicient thickness ,to rendcr the disc backing can; be constructed so as to beuseful under severe operating conditions without break- 2 down of the backing inthe unsupported portions totally infiexible infuse althoughitsis' relatively stiff in character. invention isparticularly concerned with discs of the described type in H which the discs and especially the center or abrasive-free.'central portion of thisdiscs are suitably. reinforced or strengthened against 'breakdown in'use Discs. of the 1 described type have frequently failed iniusebecauseof the breakdown of the backing in the central part of the disc where the backing, is unprotected and reinforced, by the thereof by@ reinforcing thebacking by means of This metallic disc: which constitutes one lamination of the backing is not, coextensive ingarea portion of the backing only. i Therefore, the

metallic reinforcing plate does not interfere with the operation of thedisc throughout. its useful life but. permits the abrasiveelement as well as overlying abrasive element. such failures are ing of the unprotected portionofthe backing the discs as heretofore made and provide an abrasive disc that will standup under more rigorous conditions of use.

It is a further object to provide an abrasive commonly characterized by either asuddentearvaried from thefiguregiven. 7

the underlying portion of the backing to wear away in the usual manner. has bee rfound highly satisfactory for; use as One material which thereinforcing plate is aluminum sheeting .010" to .015". in thickness, for example .012" in thickness,; although other metallic reinforcing materials may .be used such as-galvanized iron sheeting or the like and the thickness may be Referring further to the drawing, Figures 1, 2 and 3 depict an abrasive disc made in accordance "with the present invention and whichas therein disc in which the backing will resist sudden or gradual breakdownduring'operation; I

It is a still further object'to provide abrasive articles of the described type inlwhich the 'backing is suitably reinforced without interference with the ability'of the disc to wear away at the periphery.

. In order that the invention maybe more clearly understood reference ismade to'the drawings in which one particular embodiment of the present invention is shown and in which:

Figure 1 is atop plan view of an abrasive disc made in accordance with the present invention;

46 in Figurel, but in which the abrasive element Figure 2 is atop view of the abrasive disc shown and variouslaminations of the backing and reshown consists of an annular abrasive element 4 adhesively secured to one side of a backing 5 by means of an adhesive 6. The abrasive element 4 is composed of a coiled strip of abrasiveincluded'felted fibrous sheet material which; during the forming of thedisc, is compressed to form 3 PatentNo'. 2,284,738. In order to provide'an abrainforcementv are shown partially cutaway to r learly bring outthe structural features of the disc; and H 7 v c v Figure} is a vertical cross-sectional view taken alongthe line 3-3 of Figure 1.

v 3 We have discovered that abrasive discs of the described type comprising an annular abrasive element adhesively secured to a yieldable fibrous sive element having a final thickness of 4;" a

strip ofabrasive-inoluded sheet material approximately in width should be used. 1Coiled strip material of greater or lesser widths 'inay be used I in whichcase the final abrasive element will differ correspondingly in thickness. I

The disc backing is composed of alternate layers of a carded, felted or non-wovenfibrous sheet material 1 and adhesively'sizedfabric such as burlap 8. the fibrous sheet material I we prefer to use a carded cotton sheeting'such as that disclosed and described in U. S. Patent No. 2,055,410 although strong paper -or-other non-woven fibrous material may be used in its place. ,Thelayers of carded or felted fibrous materialareimpregnated with a suitable adhesive such as a rubber or synthetic rubber assonca latex, casein, thermoplastic resin, or thermosetting resin such as a plasticized phenol aldehyde resin or the like, separately or in combination. The fabric layers are also sized with a suitable adhesive of the same type or sized with a thermosetting resin such as a phenol formaldehyde resin. The impregnating and sizing adhesives are usually suflicient to serve as the combining adhesive or cement to hold the various plies of the backing and the abrasive element securely together, although additional adhesive can be used in the combining operation if desired. The central reinforcing plate 9 consists of a sheet of aluminum .012" in thickness to which is adhesively secured a surface layer of paper 10.

An abrasive disc of the type shown in Figures 1, 2 and 31s made as follows:

The various fibrous materials which comprise the backing are first impregnated or sized with suitable adhesives in any of the several ways well-known in the art such as by sprayin dipping, roll coating or the like, and the adhesively treated material dried to a condition suitable for handling. The materials are then died out or otherwise cut into disc-shapedpieces of the desired size, as, for example, '7" or 9" discs provided with arbor holes of the desired dimension, and placed in a mold in the order shown in the drawing. Hard aluminum sheeting .012" thick is then died out on a hard metal surface into I suitably arbored discs, discs of approximately 3" diameter being cut for use in abrasive discs of 7" diameter and discs of approximately diameter being cut for use in discs of 9" diameter. The aluminum is degreased and two coats of "adhesive applied to both surfaces with an air drying interval between coats of 15 minutes and a final air drying period of 30 minutes before use.- An adhesive or cement which has been found highly satisfactory under the above conditions of use is composed of the following ingredients, the percentages being by weight:

43 %-polyvinyl butyral modified-phenol formaldehyde resin (such as that known and sold by the Bakelite Corporation, of Bloomfield, New Jersey, under the trade-mark designation Bakelite No. EJ161320") 57%-alcohol thinner The adhesively coated aluminum disc together with a top disc-shaped piece of paper of equal size is then placed in the mold upon the layers of the backing and held in position in the center of the mold by an arbor pin and an overlying metal disc or plate of substantially the same diameter as the non-abrasive center. Finally, a closely coiled, 1%" wide strip of abrasive-included fibrous sheet material, such as that disclosed and described in U. S. Patent No. 2,284,738, sufilcient to cover the backing for a distance approximately 2" in from the periphery of the disc isv placed in the mold and the entire assembly hot pressed at 3500 pounds per square inch (based on the area of the abrasive element only) to adhesively combine the plies of the backing and unite them to the abrasive element to form the desired abrasive disc.

Having described the invention in detail, it is desired to claim:

1. An abrasive disc comprising an annular layer of abrasive material of a thickness which is insuflicient to render the abrasive disk rigid, said abrasive material being adhesively secured to a being reinforced by a thin metal sheet .010." to .015" thick which is substantially coextensive with the abrasive-free central area of the fibrous backing.

2. An abrasive disc comm'ising an annular layer of abrasive-containing, fibrous material of a thickness which is insufilcient to render the abrasive disk rigid, said abrasive material being adhesively secured to a flexible laminated fibrous backing, said backing being reinforced by a thin metal sheet which is substantially coextensive with the abrasive-free central area of the fibrous backing.

3. An abrasive disc comprising an annular layer of abrasive material of a thickness which is insuificient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side-of a flexible laminated fibrous backin and extending radially in from the periphery thereof, the layers of said backing being adhesively united and comprising several fibrous laminations including at least one layer of felted cotton fabric and at least one layer of burlap extending from the arbor of.the disc to the'periphery thereof, said backing being reinforced by a thin sheet metal disc incorporated as a part of the backing and extending radially out from the arbor of the disc, but substantially smaller in diameter than the fibrous laminations of said backing.

4. An abrasive disc comprising an annular layer of abrasive material of a thickness which is insuificient to render the abrasive disk rigid, said abrasive material being adhesively secured to a flexible laminated fibrous backing said backing being reinforced by a thin aluminum sheet .010" to .015" thick which is substantially coextensive with the abrasive-free central area of the fibrous backing.

5. An abrasive disc comprising an annular layer of abrasive material adhesively secured to one side of a flexible laminated fibrous backing, said backing comprising the following adhesively combined layers in the order named from the disc back surface to the abrasive side of the disc: a layer of felted cotton, 3 layer of burlap, a layer of felted cotton, a layer of burlap, a sheet of aluminum .010" to .015 thick and a layer of paper, said aluminum and paper being substantially coextensive in area with the abrasive-free central area of the fibrous backing.

6. An abrasive disc comprising an annular layer of abrasive material of, a thickness which is insuificient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a flexible laminated fibrous backing comprising a plurality of adhesively combined lays ers of felted fibrous material and woven fabric, said backing being reinforced by a thin sheet metal disc incorporated as part of the backing and extending radially outward from the arbor of the disc, but substantially smaller in diameter flexible laminated fibrous backing, said backing than the fibrous laminations of said backing.

'7. An abrasive disc comprising an annular layer of abrasive material of a thickness :which is insuiiicient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a flexible laminated fibrous backing comprising a plurality of layers of felted fibrous material and woven fabric adhesively combined by means of a heat-hardened resin, said backing being reinforced by a. thin sheet metal disc incorporated as part of the backing and extending radially outward from the arbor of the disc, but

5 substantially smaller in diameter than the fibrous laminations of said backing.

8. An abrasive disc comprising an annular layer of abrasive material of a thickness which is insufllcient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a flexible laminated flbrous backing comprising a plurality of layers of felted fibrous material and woven fabric adhesively combined by means of a heat hardened phenolic resin, said backing being reinforced by a thin sheet metal disc incorporated as part of the backing and extending radially outward from the arbor of the disc, but substantially smaller in diameter than the fibrous laminations of said backing.

9. An abrasive disc comprising an annular layer oi abrasive material of a thickness which is insufllcient ,to' render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a flexible laminated fibrous backing and extending radially in from the periphery thereof, the layers of said backing being adhesively united and comprising several fibrous laminations including at least one layer 01' paper, and at least one layer of burlap extending from the arbor of the disc to the periphery thereof, said backing being reinforced by a thin sheet metal disc incorporated as a part of the backing and extending radially out from the arbor of the disc, but substantially smaller in diameter than the fibrous laminations of said backing.

10. An abrasive disc comprising an annular layer of abrasive material 01' a thickness which is insuflicient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a. flexible laminated fibrous backing and extending radially in from the periphery thereof, the layers of said backing being adhesively united and comprising several fibrous laminations including at least one layer of ielted 9 2,320,139

resin-impregnated cotton fabric and at least one layer 0! resin-sized burlap extending from the arbor of the disc to the periphery thereof, said backing being reinforced by a thin sheet metal disc incorporated as a part of the backing and extending radially out from the arbor oi the disc, but substantially smaller in diameter than the fibrous laminations of said backing.

11. An abrasive disc comprising an annular layer of abrasive material of a thickness which is insumcient to render the abrasive disk rigid, said abrasive material being adhesively secured to one side of a flexible laminated fibrous backing comprising a plurality of resin impregnated layers of felted fibrous material and woven fabric adhesively combined bymeans of a heat-hardened resin, said backing being reinforced by a thin sheet metal disc incorporated as part of the backing and extending radially outward from the arbor oi the disc, but substantially smaller in diameter than the fibrous laminations of said backing.

GEORGE J. GOEPFERT. LOUIS L. COFRAN.

aaramincas crran The following references are of record in the Jim 01 this patent:

UNITED STATES PATENTS Number Name Date 302,952 Smith Aug. 5, 1884 583.735 Dodge June 1, 1897 1,010,040 Gardner et al. Nov. 28, 1911 1,832,515 Webster Nov. 17, 1931 2,070,764 Webster Feb. 18, 1937 2,128,213 VanDer Pyl Aug. 23, 1938 2,129,061 Ball Sept. 13, 1938 2,309,819 Benner --'Feb. 2, 1943 Kirchner May 25, 1943 a Certificate of Correction Patent No. 2,520,763 August 29, 1950 GEORGE J. GOEPFERT ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 1, line 8, for the word This read The; line 11, for this read the; line 17 for reinforced read umeinforoed;

and that the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 3rd day of July, A. D. 1951.

THOMAS F. MURPHY,

Assistant Uommz'ssz'oner of Patents. 

